DEPOSITS - Components of Interest Expense on Deposits (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Deposits [Line Items]
Interest expense on deposits	$ 16,359	$ 18,514
Amortization of broker placement fees	1,335fbp_AmortizationOfBrokerPlacementFees	1,785fbp_AmortizationOfBrokerPlacementFees
Interest expense on deposits	$ 17,694us-gaap_InterestExpenseDeposits	$ 20,299us-gaap_InterestExpenseDeposits

Aggregate amount of interest expense on all deposits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.6)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 6

-Article 9

Name:	us-gaap_InterestExpenseDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration